Fix wsgi_user and wsgi_group for RHEL

In RHEL, wsgi_user and wsgi_group should be "apache" and not
"dashboard".

Closes-bug #1224770
Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>

Change-Id: I253b90a55d33d927e318400a69243925b7245aa4